The present invention relates to a rotary scraper for treating a surface, wherein the scraper comprises a plurality of fingers projecting from a spool and the rotation of the spool impacts the fingers against the surface being scraped.
The rotary scraper is usable in various applications where scraping is desired, including removal of paint, burnishing of metal, removal of a surface layer and even removal of fish scales. In many of these situations, the surface layer to be removed is comprised of harder material than the layer beneath it which is not to be damaged, whereby if the rotary scraper has a gouging effect, once it removes the surface layer, it can do great damage to the softer layer beneath, as might occur in fish scaling, for example.
One problem with known rotary scrapers is that their fingers gouge the work surface if the scraper is not handled with great care. Various attempts have been made to eliminate gouging, including restraining the fingers from assuming undesired radial extension under the influence of centrifugal force and forming the fingers, or the means by which the fingers are attached to the spool, of resilient elastomeric material; or by making the fingers completely flexible and providing an abrasive surface at the ends thereof. See for example, U.S. Pat. Nos. 3,958,294 and 3,872,630.
In known rotary scrapers, the fingers are arrayed in a plurality of rows of fingers, angularly spaced apart around a spool. Each row of fingers extends longitudinally across the spool in a row generally parallel to the axis of the spool. Typically, each row of fingers is comprised of the same number of fingers and/or all of the fingers in each of the angularly spaced apart rows are at the same respective longitudinal positions across the spool, whereby any cross section through the spool and through any fingers of any row of fingers will also pass through the corresponding finger on every other row. When the scraper spool is rotated rapidly, and if the scraper is held stationary in use for any significant period, the work surface will be gouged by all of the aligned fingers striking the surface at the same spot and tracking a single swath across the work surface.
Typically, the fingers of the rotary scrapers are generally circular in cross section, whereby their leading impacting edge is quite narrow and relatively sharp. This increases the gouging effect.